You can certainly do that (perc/occ). I keep a juvenile occelaris in a 15 gallon nano with a Scotts damsel, purple basslet (no this one isn't a bully, oddly), a very small yellow watchman goby and some other goby that I caught at the beach. I do have one sailfin molly in there that just doesn't fit in, but the occellaris does great. I'm sure I could keep two if I wanted to. Just don't get too excited about keeping an anemone with occellaris if they are tank-bred. They just don't seem to give a dern about anemones.